Giori Published Patent Application US 2005/0084634 (also published as WO 2005/041827) discloses a biodegradable and toilet-flushable body waste collection pouch, and an appliance and method in which such a pouch constitutes the inner pouch of a peelably separable pouch-in-pouch system. The walls of the inner pouch are composed of an ultra-thin, heat-sealable film impermeable to body wastes comprising a plasticized biodegradable polyester or copolyester externally covered by a soft and water-disintegratable cover layer of biodegradable and water-dispersible fibers. The cover layer and film are weakly bonded together in such a way as to avoid pinholes in the film that might otherwise be caused by the fibers. When used as the inner pouch of a pouch-in-pouch system, the film of the outer pouch is selected to have a melting temperature higher than that of the inner pouch film, with the result that a peripheral heat seal joining the walls of the two pouches together will allow the walls of the outer pouch to be peeled away without delaminating the film and cover layers of the inner pouch.
Pedersen et al Published Patent Application US 2005/0113770 (also published as WO 2005/041828) discloses an ostomy appliance having a face plate assembly and inner and outer pouches joined thereto. The outer pouch is provided with one or more peripherally-extending sealing seams that allow the walls of the outer pouch to be separated by peeling forces applied in directions transverse to such seam or seams. In preferred embodiments, the sealing seams also peelably join the peripheral edges of the outer pouch to those of the inner pouch. A method of disposing of the pouch assembly of such an ostomy appliance is also disclosed.
The disclosures of these aforementioned published applications US2005/0084634 and US 2005/0113770 are fully incorporated in this application by reference.
It has now been found that the flushability of a biodegradable pouch as disclosed in these published applications, and the passage of such a pouch through a sewer system, are greatly enhanced if the water-dispersible fibers along at least a portion of the outer surface of the pouch's cover layer (which is preferably formed of a nonwoven material, particularly a water-disintegratable paper such as cellulosic toilet tissue) are provided with a hydrophilic coating. The coating does not impair the peelability of the seals of a pouch-in-pouch system or interfere with the water dispersibility of the fibers, and is found to be advantageous because it reduces the friction between the outer surface of the pouch and the walls of a flush toilet and passages of a sanitary sewer system. While the coating would normally be applied and dried during production of such a pouch or pouch assembly, or during the tissue paper-film manufacture, it is contemplated that alternatively such a coating might be applied by a user, as by spraying, just prior to discarding the pouch and its contents into a flush toilet.
When applied in production, the coating in the form of a water-based hydrophilic solution is sprayed, rolled, or otherwise applied to the surface of the pouch's tissue cover layer. It is then dried by any suitable means, as in a convection oven. When the pouch is later discarded into the water of a flush toilet, the coating absorbs water and reactivates a hydrophilic film that makes the surface of the pouch slippery, significantly reducing the friction between the pouch and the walls of the toilet and sewer passages. This reduced surface friction has a positive impact on the flush performance of the pouch.
The biodegradable coating contains one or more lubricating agents. One preferred gelling agent is hydroxyethylcellulose, available under the commercial name “Natrosol” from Aqualon, but other lubricating agents considered suitable are hydroxypropylcellulose, carboxymethylcellulose and their salts, guar gums, gelatin, pectin, polyethylene glycol, polyethyleneoxide, polyacrylamides, acrylic acid polymers and their salts, and water-soluble silicone gelling agents. Of particular importance is that such a lubricating agent, after drying following initial exposure to water, must be capable of again becoming water soluble and slippery when re-exposed to water. Thus, it has been found that polyvinyl alcohol is unsuitable as a gelling agent for use in this invention because although it becomes slippery upon initial hydration, once it has dried it is no longer water-soluble. A lubricating agent for use in this invention must be capable of rewetting/redesolving to avoid the risk that the drying of the coating might cause a pouch to stick to the wall of a sewer pipe and not readily release when water is again flushed through the pipe.
In addition to a lubricating agent or agents, the coating material may include preservatives, surfactants, thickeners, pH buffers, slip agents, odor neutralizers, deodorants and other additives. Examples of thickeners include, but are not limited to, carbomers, gums, poloxamers, gelatin, pectin and nonionic, zwitterionic and ionic gel formers.
By way of example, a coating solution of 2% hydroxyethylcellulose (Natrosol) and 0.3% Phenonip (a commercial mixture of preservatives containing phenoxyethanol, methylparaben, ethylparaben, propylparaben butylparaben and isobutylparaben) may be applied to the paper tissue layer (25 g Shawano cellulosic tissue code 3040 from Shawano Specialty Papers) of a waste collection pouch as disclosed in the aforementioned published applications, the disclosures of which are incorporated herein by reference. The coating is then dried by placing the pouch in a convection oven at 75° C. for approximately one hour. Drying may also be achieved by using infrared lamps, heating elements or other sources of heat, and may be boosted by negative pressure and air circulation.
The desired load of coating may be achieved in single or multiple applications.
It has been found that an inner pouch of the type disclosed the aforementioned published applications, formed of an ultra thin biodegradable film with a tissue covering layer but without the hydrophilic coating described herein, may be safely flushed through a toilet with a pouch load of up to about 110 g, whereas if the tissue layer of a similar pouch is provided with the hydrophilic coating of this invention, the pouch load may be safely and effectively increased to 150 g.